Projection lens and method of using same

摘要

A new and improved projector lens arrangement which can automatically adjusted for focusing purposes in an easily and convenient manner according to a novel focusing method of the present invention. The projection lens arrangement generally includes three groups of optical elements aligned along a common optical axis with a variable vertex length and wide field coverage angle. One element group near the object is a doublet having a negative element with a concave surface and a positive element being bi-convex having one surface near the image complementarily shaped to the concave surface of the negative element.